On a combined influence of long-term solar activity variations and geomagnetic dipole changes on climate change.

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Abstract	Abstract. The influence of variations in galactic cosmic rays (GCR) on climate change has been analyzed for the time intervals of thousands and tens of thousands of years. It has been shown that in the last millennium quasi-two-hundred-year variations in the GCR intensity (variations in the cosmogenic 14C isotope concentration in dated tree rings) modulated by solar cyclicity (the ~210-year cycle) correlated well with climate change (temperature and precipitation variations). The correlation coefficient between variations in GCR and climate parameters for different regions of the Earth has been found to range from 0.58 to 0.95. Analysis of variability in the concentration of the cosmogenic 10Be isotope (that also reflects the GCR flux variability) in Greenland ice for the time interval from 20,000 to 50,000 years ago has revealed that the 10Be concentration is modulated by the quasi-two-hundred-year solar cycle. Comparison of variations in the cosmogenic 10Be isotope concentration with changes in the magnitude of the virtual axial dipole moment (VADM) of the geomagnetic field has shown that the envelope of the 10Be concentration amplitude correlates well with the VADM variations. Thus, it can be concluded that long-term solar activity and geomagnetic dipole variations exert a combined influence on the GCR fluxes that enter the Earth’s atmosphere and affect the climate. A decrease in the geomagnetic dipole leads to an enhancement of the total GCR flux on the one hand and an increase in the depth of modulation of the GCR fluxes caused by solar activity variability on the other hand. 1
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Subject Keyword	Climate Change Isotope Concentration Gcr Flux Time Interval Long-term Solar Activity Total Gcr Flux Different Region Vadm Variation 210-year Cycle Gcr Intensity Correlation Coefficient Solar Activity Variability Dated Tree Ring Geomagnetic Field Quasi-two-hundred-year Solar Cycle Geomagnetic Dipole Gcr Flux Variability Precipitation Variation Geomagnetic Dipole Variation Virtual Axial Dipole Moment Galactic Cosmic Ray Climate Parameter Combined Influence Concentration Amplitude Correlate Greenland Ice Solar Cyclicity Last Millennium Quasi-two-hundred-year Variation
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